38. 1-Wire

38.1. Overview

This example shows that accessing a digital temperature sensor DS18B20 via 1-wire bus.

HPM 1-Wire features as follows:

• 1-Wire Master

• Reset and Presence Pulses output and 1-Wire Slave detection

• single or multiple byte read and write

• DMA mode

• SRA mode

• Interrupt

38.2. Board Setting

None

38.3. Background

1-Wire(single bus) is a peripheral serial expansion bus technology bus launched by DALLAS company, as the name suggests, it is the use of a signal line for communication, both the transmission of clock signals and data transmission, and can carry out two-way communication, with saving I/O port lines, simple resource structure, low cost, easy to expand and maintain the bus and many other advantages. Commonly used single-bus devices are generally stable sensors, EEPROM, unique serial number chips, such as DS18B20, DS243 and so on.

38.4. Running the example

• Running log is shown in the serial terminal as follows

  This is a onewire sample: DS18B20
  OWR Slave Detected!
  Family Code: 28
  Serial Num:67 e2 79 00 00 00
  CRC: 3a
  Thermometer resolution: 12 bit
  Current Temp: 26.94 degree centigrade
  Current Temp: 26.94 degree centigrade
  Current Temp: 26.87 degree centigrade
  Current Temp: 26.94 degree centigrade
  Current Temp: 26.87 degree centigrade
  Current Temp: 26.87 degree centigrade
  Current Temp: 26.94 degree centigrade
  Current Temp: 27.25 degree centigrade
  Current Temp: 27.69 degree centigrade
  Current Temp: 28.06 degree centigrade
  Current Temp: 28.31 degree centigrade
  Current Temp: 28.50 degree centigrade
  Current Temp: 28.62 degree centigrade
  Current Temp: 28.44 degree centigrade
  Current Temp: 28.31 degree centigrade
  Current Temp: 28.19 degree centigrade
  Current Temp: 28.06 degree centigrade